The invention is concerned with a process and a device for cold milling rubber granulate in a pinned disk mill.
The pinned disk mill is frequently used for the milling of soft to medium hard materials. It consists in principle of two disks with several rows of pins mounted in a concentric circle. One disk plate rotates very fast while the other rotates slowly or is standing still. The particles of the material to be milled bounce with a high velocity onto the pins and are thereby reduced in size.
The fine milling of rubber granulate in studded or toothed disk mills is well known. Since rubber is very soft at room temperature, it is therefore necessary, when fine milling in other mills, to embrittle the rubber granulate before or, if necessary, during the milling process. This is done by cooling, for example, with liquid nitrogen. It has been demonstrated thereby that the specific nitrogen consumption, e.g. the nitrogen consumed per kg. of rubber granulate, is relatively high. There results additionally, a considerable amount of wear of the miling parts because the embrittled rubber granulate is quite abrasive. Furthermore, as for example, with pinned disk mills, the throughput capacities attainable for rubber granulate are small compared to that for other materials.